There seems to be some confusion here between “you must have a goal” and “you must have a single over-arching goal”. Rationality is a bunch of strategies for thinking effectively; in order to do that, you must have something to think about. That’s almost tautological. If you only have a series of easy goals with time horizons less than a day, you can still apply rationality to achieving them. It’s just that you’ll exercise and develop your rationality more if you have goals that are challenging; and in particular, it helps to have goals that are broad enough that you can pause at any time, ask which goal the thing you’re presently doing serves, and know that you’ve made a mistake if you can’t answer.
There seems to be some confusion here between “you must have a goal” and “you must have a single over-arching goal”. Rationality is a bunch of strategies for thinking effectively; in order to do that, you must have something to think about. That’s almost tautological. If you only have a series of easy goals with time horizons less than a day, you can still apply rationality to achieving them. It’s just that you’ll exercise and develop your rationality more if you have goals that are challenging; and in particular, it helps to have goals that are broad enough that you can pause at any time, ask which goal the thing you’re presently doing serves, and know that you’ve made a mistake if you can’t answer.